Incoming Calls Not Ringing

I got my Droid 4 yesterday, upgrading from a Droid. This morning my daughter called me twice but the phone never rang. She called on the landline, and I told her to call me back when she hung up. She did and the phone did ring. I happened to have the phone sitting next to me and the screen lit up and showed she was calling me again, but it never rang. I've checked my Settings and it's set to Call Only, and the volume ringtone is turned up all the way. What's wrong and how can I fix it? Thanks!

It seems to be working now. The only other thing I can figure out is the little button between the camera and unlock slides was set on silent. I'm going to have to watch and make sure I don't swipe that when I swipe unlock. Thanks!